Guide and flexible sleeve for use with catheters

ABSTRACT

Embodiments of a guide and flexible sleeve for use with catheters for ablation or other medical procedures are disclosed. An exemplary catheter comprises a guide element having a proximal end and a distal end, the distal end configurable in a desired shape. A flexible sleeve is conformable to the guide element so that the flexible sleeve slides over the guide element, the flexible sleeve has a proximal end and a distal end. A controller couples to the flexible sleeve. The controller operates to move the flexible sleeve at least part way between the distal end of the guide element and the proximal end of the guide element. At least one ablation element disposed at the distal end of the flexible sleeve operates to form a substantially continuous ablative lesion when the flexible sleeve is in contact with a contiguous volume of target tissue.

BACKGROUND OF THE INVENTION

a. Field of the Invention

This invention relates generally to medical instruments, and, morespecifically, to a guide and flexible sleeve for use with catheters forablation or other medical procedures.

b. Background Art

Catheters are flexible, tubular devices that are widely used byphysicians performing medical procedures to gain access into interiorregions of the body. Careful and precise positioning of the catheterswithin the body is important to successfully completing such medicalprocedures. It is well known that benefits can be and/or are gained byusing catheters to form lesions in tissue if the depth and location ofthe lesions being formed can be controlled. For example, it can bedesirable to elevate tissue temperature to around 50° C. until lesionsare formed via coagulation necrosis, which changes the electricalproperties of the tissue. Lesions can be and/or are formed at specificlocations in cardiac tissue via coagulation necrosis to lessen oreliminate undesirable atrial fibrillation.

Several difficulties can be and/or are encountered, however, whenattempting to form lesions at specific locations using some existingablation electrodes. One such difficulty encountered with existingablation catheters is how to locate the tissue and maintain cathetercontact with the tissue at the desired location during the procedure.These assessments are not readily determined using conventionalfluoroscopy techniques. Instead, the physician locates and maintainscontact between the catheter and the tissue based on his/her experienceusing the catheter. Such experience only comes with time, and can beand/or are quickly lost if the physician does not use the catheter on aregular basis. In addition, when forming lesions in a heart, the beatingof the heart further complicates matters, making it difficult tomaintain sufficient contact pressure in a fixed location between thecatheter and the tissue for a sufficient length of time to form adesired lesion. If the contact between the catheter and the tissuecannot be properly maintained, a quality lesion is unlikely to becreated.

BRIEF SUMMARY OF THE INVENTION

It is desirable to be able to maintain contact and create desiredlesions in tissue, including in a moving surface (e.g., the heart wall).In various embodiments, a guide and flexible sleeve for use withcatheters for ablation or other medical procedures are disclosed. Theguide can be and/or is preformed (i.e., prior to the procedure) to adesired shape (e.g., a circular shape). Once positioned adjacent atissue to be ablated, one or more ablation element can be and/or areactivated and the flexible sleeve can be and/or is retracted from adistal end of the guide to form a lesion substantially conforming to theshape of the guide that is in contact with the tissue. The cathetersdisclosed herein can be and/or are used to make spot or linear lesionsalong the length of the guide according to the shape of the guide.

In an exemplary embodiment, a catheter can comprise a guide elementhaving a proximal end and a distal end, the distal end configurable in adesired shape. A flexible sleeve is conformable to the guide element sothat the flexible sleeve slides over the guide element, the flexiblesleeve has a proximal end and a distal end. A controller is attached tothe flexible sleeve. The controller is operable to move the flexiblesleeve at least part way between the distal end of the guide element andthe proximal end of the guide element. At least one ablation element isprovided at the distal end of the flexible sleeve. The at least oneablation element is operable to form an ablative lesion when theflexible sleeve is in contact with a target tissue.

In another exemplary embodiment, a catheter comprises a unitary flexibletubing having a proximal end and a distal end defining substantially anentire length of the catheter. A guide element is provided having aproximal end and a distal end, the distal end preformed in a desiredshape. A flexible sleeve is conformable to the guide element so that theflexible sleeve slides over the guide element, the flexible sleevehaving a proximal end and a distal end, the combination guide elementand flexible sleeve insertable through the unitary flexible tubing. Acontroller is attached to the flexible sleeve and extending through theunitary flexible tubing for operation outside of a patient's body, thecontroller operable to affect travel of the flexible sleeve over theguide element in two directions. At least one ablation element isprovided at the distal end of the flexible sleeve, the at least oneablation element operable to form an ablative lesion when the flexiblesleeve is in contact with a target tissue.

In yet another exemplary embodiment, a catheter comprises a flexibletubing defining substantially an entire length of the catheter. Guidemeans is provided having a proximal end and a distal end, the distal endpreformed in a desired shape. A flexible sleeve is conformable to theguide means so that the flexible sleeve slides over the guide means, theflexible sleeve having a proximal end and a distal end, the guide meansand flexible sleeve insertable through the flexible tubing forpositioning adjacent a tissue. Control means is attached to the flexiblesleeve and extending through the flexible tubing for operation outsideof a patient's body to move the flexible sleeve back and forth over theguide means. Ablation means is provided at the distal end of theflexible sleeve, the ablation means operable to form an ablative lesionwhen the flexible sleeve is in contact with a target tissue.

In still further embodiments, the guide element is a guide wire and/or amapping catheter. The guide element can be and/or are preformed in thedesired shape. The desired shape of the guide cancan be and/or are,e.g., circular. A collar can be and/or are provided on the distal end ofthe guide element, the collar stopping travel of the flexible sleevewhen the flexible sleeve comes into contact with the collar. The guideelement can include an irrigation conduit with at least one irrigationport.

In still further embodiments, the flexible sleeve is positioned at thedistal end of the guide element initially during an ablation procedure,and the guide element is retracted toward the proximal end of the guideelement during the ablation procedure, wherein retrograde motion createsa lesion on the tissue substantially conforming to the desired shape ofthe guide element. The flexible sleeve can include an insulated portionand an active portion. The insulated portion is provided over aconducting portion. The conducting portion is electrically connected tothe active portion, the conducting portion delivering electrical energyto the active portion, and the active portion is the ablation element.

In other embodiments, the ablative element includes at least oneelectrode mounted to an outer surface of the flexible portion. At leastone sensor can be and/or are mounted to an outer surface of the flexibleportion. For example, the sensor can be and/or are a thermistor,thermocouple, a mapping sensor, or a contact sensor.

Still other features of a guide for catheters are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first exemplary catheter.

FIG. 2 is a magnified view of a distal end portion of the catheter shownin FIG. 1.

FIGS. 3a-d show the tip assembly 14 as it can be and/or are moved overthe guide element.

FIG. 4 shows another embodiment of the tip assembly.

FIG. 5 shows another embodiment of the tip assembly.

FIG. 6 shows a close up view of another tip assembly 314 which might beimplemented with an irrigated catheter.

FIG. 7 shows another flexible sleeve which can be and/or are implementedwith a tip assembly.

FIG. 8 shows a tip assembly having a guide element and the flexiblesleeve from FIG. 7.

FIGS. 9a-b shows the flexible sleeve in (a) a fully extended positionrelative to the guide element; and (b) in a fully retracted positionrelative to the guide element.

FIGS. 10a-e shows the tip assembly from FIG. 8 and illustrates how theflexible sleeve can be and/or are moved over the guide element.

FIG. 11 shows another tip assembly having a generally linearconfiguration.

FIG. 12 shows another tip assembly having a generally flattenedsemi-circular configuration.

FIGS. 13a-b show another tip assembly having a guide wire guide elementand a flexible sleeve, wherein (a) shows the flexible sleeve a fullyextended position relative to the guide element; and (b) in a fullyretracted position relative to the guide element.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of a guide and flexible sleeve for use withcatheters for ablation or other medical procedures, along with methodsfor creating ablative lesions, are depicted in the figures. Exemplarysystems comprise a catheter which can be and/or are inserted into thepatient, e.g., an ablation catheter for forming ablative lesions insidethe patient's heart. During an exemplary ablation procedure, a user(e.g., the patient's physician or a technician) can insert the catheterinto one of the patient's blood vessels, e.g., through the leg or thepatient's neck. The user, guided by a real-time fluoroscopy imagingdevice, moves the catheter into the patient's heart.

When the catheter reaches the patient's heart, sensors at the distalportion of the catheter can be and/or are implemented to electricallymap the myocardium (i.e., muscular tissue in the heart wall) and locatea target tissue. After locating the target tissue, the user moves thecatheter into contact with the target tissue before applying ablativeenergy to form an ablative lesion or lesions. Implementing the guidehaving a preformed shape and sliding the flexible sleeve over the guideduring the ablation procedure, the user is able to provide theappropriate level of contact at the target area in order to form qualityablative lesions without damaging surrounding tissue in the heart orother tissues or anatomical structures elsewhere in the patient's body.

Accordingly, embodiments of the present invention provide a number ofadvantages, including, for example, the ability to apply a reasonableamount of ablative energy to a target tissue while mitigating tissuecontact problems. The invention also facilitates enhanced tissue contactin difficult environments (e.g., during lesion formation on a movingsurface inside a beating heart, and adjacent other sensitive tissues oranatomical structures).

FIG. 1 illustrates one type of an exemplary single-use catheter 10generally including a flexible tubing 12, a tip assembly 14, a Yconnector 16, a luer device 18, and an electrical connector 20. Theelectrical connector 20 establishes electrical connection with a powersource (not shown) that operates ablative element(s) and/or sensors atthe tip assembly 14 to perform, for example, ablation procedures,mapping or pacing procedures, or to perform other aspects of a medicalprocedure.

Although it will become evident that aspects of the exemplary catheter10 are applicable to a variety of medical procedures and end uses, theinvention will be described principally in the context of a specificexample of an ablation catheter. Specifically, the catheter 10 as shownin FIG. 1 is believed to be particularly advantageous as an ablationcatheter for creating endocardial lesions during cardiac ablationprocedures to treat arrhythmias, and also for cardiacelectrophysiological mapping and delivering diagnostic pacing stimuli.However, the invention and the appended claims are not intended to belimited to any specific type of catheter (e.g., steering catheters canalso be used), including but not limited to specific examples orembodiments described herein, except when explicitly defined as such inthe appended claims.

The Y-connector 16 separates a fluid tube 22 from electrical lead wiresextending between the tip assembly 14 and the electrical connector 20.That is, the fluid tube 22 and the lead wires forward of the Y-connector16 pass internally through The tubing 12, while aft of the Y-connector16, the fluid tube 22 and the wire leads are exposed and separated forconnection to a fluid source (not shown) and a power source,respectively. The electrical connector 20 can be and/or is a knownconnector that can be and/or is engaged to a power source or powersupply with, for example, plug-in connection. One suitable electricalconnector is a 14 pin REDEL® plastic connector commercially availablefrom LEMO of Rohnert Park, Calif., although other connectors fromvarious manufacturers can likewise be utilized.

The luer device 18 in the depicted embodiment, as known in the art, canbe and/or is used to open or close a flow path so that fluid can beand/or is passed through the Y-connector 16 and the tubing 12 to the tipassembly 14 for irrigation purposes. The luer device 18 can be and/or isconsidered optional for certain procedures.

The flexible tubing 12 includes a proximal end 24 coupled to theY-connector 16, a distal end 26 coupled to the tip assembly 14, and anaxial length extending between the proximal and distal ends 24 and 26.In general, the flexible tubing 12 can be and/or is fabricated accordingto known processes, such as extrusion processes. The tubing 12 can beand/or is fabricated from any suitable tubing material known in the artof medical instruments, such as engineered nylon resins and plastics,including but not limited to PEBAX® tubing of Ato Fina Chemicals,France.

In an exemplary embodiment, the tubing 12 includes a first portion 28 ofthe tubing 12 between the Y connector and the tip assembly 14, and asecond portion 30 of the tubing 12 including the distal or end portionof the tubing 12 extending to the tip assembly 14. In an exemplaryembodiment, the first portion 28 and the second portion can be and/orare fabricated from different materials, grades of materials, and/orthicknesses of materials for enhanced performance and flexibility of thetubing 12 in use of the catheter assembly 10, as will be explained inmore detail below. It is noted, however, that although the tubing 12 canhave different portions or “zones”, the tubing 12 is manufactured as aunitary piece.

For example, in one embodiment, the first portion 28 of the tubing 12can include, for example a braided material that is comparatively rigidand kink resistant. The first portion 28 can be and/or is formed withdifferent portions of braided material, semi-soft material, and softmaterial fused to one another so that the first portion 28 becomesincreasingly flexible along the axial length as the tube portion 28approaches the second portion 30. The second portion 30 of the tubing 12can include a soft and flexible material. In the illustrated embodiment,each of the tubing portions 28 and 30 share a common outside diameterof, for example, 7 French, although in other embodiments, the tubingportions 28 and 30 can be and/or are another size.

Additionally, and as shown in FIG. 1, the first portion 28 extends forthe vast majority of the axial length of the tubing 12 between theproximal end 24 and distal end 26. The second portion 30 of the tubing12 extends for a much shorter length than the first portion 28. By wayof example only, in a specific embodiment the first portion 28 extendsfor an axial length of about 126.3 cm, the second portion 30 extends foran axial length of about 0.8 cm to 2.2 cm, although other relativelengths of the tube portions can likewise be employed in otherembodiments. The different relative lengths of the tube portions 28 and30, as well as the different flexible properties of the tube portions 28and 30, allows the tip assembly 14 to be more precisely positionedwithin a patient's body, while also avoiding problems of kinks andexcessive deflection of the tubing 12 along the majority of its lengthduring use and handling.

Also in exemplary embodiments, the catheter 10 can be constructed tohave different flexibilities along the length of tubing 12, particularlyin the distal region. Typically, the distal end 26 (where the tipassembly 14 is located) is desired to be the most flexible. The proximalend 28 is desired to have less flexibility. Still additional portionscan be and/or are provided, with the proximal portions having less andless flexibility.

The flexibility can be determined by material properties and/orthickness. Thus, the tubing 12 can be made to have varying materialproperties along its length toward the distal end, so that the differentportions will have different flexibilities. The shaft can also decreasein thickness toward the distal end 26. A thinner wall of the tubing 12results in greater flexibility, while a thicker wall of the tubing 12results in less flexibility. Flexibility can change eithercontinuously/gradually or in abrupt steps.

The unitary construction of the flexible tubing of the catheter 10 isbelieved to provide manufacturing benefits, and also performancebenefits, in relation to conventional, and more complicated, catheterconstructions for use with stereotactic systems. The catheter 10 can bemanufactured without joints, ensuring high reliability and safety of thecatheter 10. The unitary tubing is easier to manufacture, and takes lesstime to manufacture. Eliminating junctions in the shaft also reduces oraltogether eliminates undesirable stiffness. The unitary flexible tubingcan extend along substantially the entire length of the catheter body,and can have a distal end to be coupled to the tip assembly 14 and aproximal end to be coupled to a handle (not shown). Alternatively, theunitary flexible tubing can extend along a portion of the catheter body,but can be and/or is attached to additional components to form theentire length of the catheter body. For example, the unitary flexibletubing with no fused connections can be and/or is fused with anotherflexible tubing to form the entire length of the catheter body.

In operation, the distal end of the catheter 10 including the tipassembly 14 is navigated to the site in the body where a medicalprocedure, such as an atrial mapping, pacing and ablation are to occur.The distal end can extend, for example, into a heart chamber of apatient. Once the distal end is in the chamber, imaging techniques canbe and/or are utilized to precisely position the tip assembly 14 forperformance of the procedure at a specific location, as will bedescribed in more detail below.

It is noted that other components typical of systems which areconventionally implemented for tissue ablation or for other therapeuticprocedures implemented via catheters (e.g., delivery of a drug ortherapeutic agent) are not shown or described herein for purposes ofbrevity. Such components can nevertheless also be provided as part of,or for use with, the catheter 10. For example, these systems commonlyinclude or are used in conjunction with an ECG recording system, and/orvarious controls for performing the ablation procedure. Such componentsare well understood in the medical devices arts and therefore furtherexplanation is not necessary for a complete understanding of theinvention.

FIG. 2 is a magnified view of a tip assembly 14 of the catheter 10 shownin FIG. 1. The tip assembly 14 can be and/or is coupled to the tubeportion 12 at one end and provide through a sheath (not shown) forinsertion through the patient's body.

The tip assembly 14 can include a guide element 32 having a proximal end34 and a distal end 36. The length of the guide element 32 extendingbetween the proximal end 34 and the distal end 36 of the tip assembly 14can be and/or is configurable in a desired shape. For example, guideelement 32 can be and/or is a guide wire which is formed in a helical,circular shape, as shown in FIG. 2. Of course any suitable shape can beand/or is employed (e.g., semi-circular, oval, rectangular, triangular,etc.).

The tip assembly 14 can also include a flexible sleeve 38 having aproximal end 40 and a distal end 42. The flexible sleeve 38 is made of amaterial which enables the flexible sleeve 38 to conform to the shape ofthe guide element 32 so that the flexible sleeve 38 can be slid over theguide element 32. In an exemplary embodiment, the flexible sleeve 38 ismade of a biologically compatible plastic or polymer material.Alternatively, the flexible sleeve 38 can be and/or is made of anymaterial and provided with a suitable coating (e.g., Teflon® coating).

The tip assembly 14 is particularly suited for ablation procedureswherein radio frequency waves are delivered at the site of an abnormalpathway in the body. Radiofrequency (RF) energy can therefore be coupledto biological tissue surrounding the catheter tip. Ablation proceduresare typically used, for example, within the interior chambers of theheart to thermally ablate cardiac tissue.

In this regard, the flexible sleeve 38 can include at least one ablationelement 44 near the distal end 42 of the flexible sleeve 38. Theablation element 44 can be and/or is energized for an ablationprocedure, as is well known in the medical devices arts, for example,using RF energy. Accordingly, the ablation element 44 is operable toform an ablative lesion when the ablation element 44 on the flexiblesleeve 38 are in contact with a target tissue.

In an exemplary embodiment, the ablation element 44 includes one or moreelectrodes. In FIG. 2, three ring electrodes 46 a-c are shown. However,any suitable number and/or type of electrodes can be and/or areprovided, and will depend at least to some extent on designconsiderations and the intended end-use. The electrodes 46 a-c arespaced from one another by dielectric materials as is known in the art.In one example, the electrodes 46 a-c can be and/or are 8 Fr electrodesthat are, for example, 2 mm in height. The electrodes 46 a-c can beand/or are fabricated from 90% platinum and 10% iridium, or othermaterials known in the art. The electrodes 46 a-c can be and/or arevisually recognizable under fluoroscopic exposure. While each electrode46 a-c is formed as an integral unit, the individual electrodes 46 a-ccan include multiple electrode elements. The electrodes 46 a-c canadditionally be operated to record intracardiac signals and to providepacing signals.

A controller 48 can be and/or is operatively associated with the tipassembly. In an exemplary embodiment, the controller 48 can include oneor more pull wires 50 a-b attached to the flexible sleeve 38 andextending through the tubing 12 of the catheter 10 (shown in FIG. 1) andout the electrical connector 20 near the handle 16 of the catheter 10,so that the pull wires 50 a-b are operable by the user. The pull wires50 a-b can further be connected to a lever arm or rotational device (notshown) that is provided on or near the catheter handle to facilitatepositioning and operation by the user. Regardless of the specificimplementation, operation of the pull wires 50 a-b by the user enablesthe flexible sleeve 38 to travel in two directions, as illustrated bythe arrows shown in FIGS. 3a and 3d . This travel moves the flexiblesleeve 38 at least part way between the distal end 36 of the guideelement 32 and the proximal end 34 of the guide element 32. Exemplarymovement of the flexible sleeve 38 for an ablation procedure can beand/or is better understood with reference to FIGS. 3a -d.

FIGS. 3a-d show the tip assembly 14 as it can be and/or is moved overthe guide element 32. In FIG. 3a , the flexible sleeve 38 is shown as itcan be and/or is moved into a fully extended position. In the fullyextended position, the distal end 42 of the flexible sleeve 38 is at thedistal end 36 of the guide element 32 (see FIG. 2). During and exemplaryprocedure, the flexible sleeve 38 is moved to the fully extendedposition prior to contacting the tissue and beginning the procedure.Once positioned against the tissue in the desired location, the ablativeelement 44 can be and/or is activated, e.g., by delivering RF energy tothe ring electrodes 46 a-c. Once a sufficient lesion has been formed inthe fully extended position, the user can gradually retract the flexiblesleeve 38, e.g., by operating the controller 38 to withdraw the flexiblesleeve 38 generally in the direction of arrow 48 a in FIG. 3a so thatthe flexible sleeve 38 is in a partially retracted position asillustrated in FIG. 3b . The user can continue to retract the flexiblesleeve 38 (again, by operating the controller 38) to withdraw theflexible sleeve 38 generally in the direction of arrow 48 b in FIGS. 3band 38c in FIG. 3c so that the flexible sleeve 38 continues to retractas illustrated in FIG. 3c , until the flexible sleeve 38 is in a fullyretracted position, as illustrated in FIG. 3 d.

It is noted the operation illustrated in FIG. 3a-d is not intended toillustrate discrete positions of the flexible sleeve 38, but rather toillustrate general movement from a fully extended position (as shown inFIG. 3a ) wherein the distal end 42 of the flexible sleeve 38 is at thedistal end 36 of the guide element 32; to a fully retracted position (asshown in FIG. 3d ) wherein the distal end 42 of the flexible sleeve 38is at the proximal end 34 of the guide element 32. It is also noted thatthis motion can be and/or is a “fluid” or “smooth” motion (e.g., wherethe user moves the flexible sleeve 38 at a constant velocity); or themotion can be and/or is more segmented (e.g., where the user moves theflexible sleeve 38 to various positions and maintains the flexiblesleeve 38 at one or more of these positions for a period of time).Specific operation will depend on the desired end-result, among otherconsiderations for lesion formation.

FIG. 4 shows another embodiment of the tip assembly 114. It is notedthat 100-series reference numbers are used to refer to like componentsalready described above, and therefore cannot be described again herewith reference to FIG. 4.

In this embodiment, the tip assembly 114 also includes a flexible sleeve138 having an ablation element 144 with ring electrodes 146 a-c. Theflexible sleeve 138 conforms to a guide element 132. However, in thisembodiment, the guide element 132 includes a collar 150 at the distalend 136. The collar 150 can have any suitable configuration, such as anend cap, rounded tip, etc. The collar 150 is provided to stop travel ofthe flexible sleeve 138 when the flexible sleeve 138 comes into contactwith the collar 150. Accordingly, the flexible sleeve 138 does notoverrun the guide element 132. In addition, the user receives tactilefeedback so that the user can know when the flexible sleeve 138 isproperly positioned in the fully extended position (e.g., as shown inFIG. 3a ).

FIG. 5 shows another embodiment of the tip assembly 214. It is notedthat 200-series reference numbers are used to refer to like componentsalready described above, and therefore cannot be described again herewith reference to FIG. 5.

The tip assembly 214 includes a flexible sleeve 238 having an ablationelement 244 with ring electrodes 246 a-c. The flexible sleeve 238conforms to a guide element 232. In this embodiment, the guide element232 includes a guide wire 252 provided with a coating 254. The guidewire 252 can be and/or is a metal, plastic or polymer which can beand/or is either preformed during manufacture or by the user (e.g.,prior to introducing the guide wire into the catheter sheath). Thecoating 254 can be and/or is any coating suitable for use in abiological system (e.g., Teflon® coating). In addition to blunting thedistal end 236, the coating 254 serves as a barrier and keeps the guidewire 252 from being exposed to the tissue.

FIG. 6 shows a close up view of another tip assembly 314 which might beimplemented with an irrigated catheter. In FIG. 6, only the distal end336 of the guide element 332 is shown. It is noted that 300-seriesreference numbers are used to refer to like components already describedabove, and therefore cannot be described again here with reference toFIG. 6.

The tip assembly 314 includes a flexible sleeve 338. The flexible sleeve338 conforms to a guide element 332. In this embodiment, the guideelement 332 includes a lumen 356 formed along the length of the centralaxis of the guide element 332. The guide element 332 can be and/or is,for example, a braided polyimide tube that maintains the flow paththrough the lumen 356 in all orientations of the tip assembly 314,without compromising the flexibility of the tubing. The distal end 336of the guide element 332 is fitted with an irrigated collar 358including one or more irrigation ports 360. The lumen 356 is in fluidcommunication with the luer 18 (FIG. 1) on one end and with theirrigation ports 360 of the tip assembly 314 at the other. The distalend 336 of the guide element 332 can be and/or is closed. Or the distalend 336 of the guide element 332 can be and/or is open, thereby forminganother fluid port. In any event, an irrigation fluid, such as saline,can be and/or is injected through the tip assembly 314. Fluid can beand/or is enabled to flow through the catheter 10 and be released at thetissue, e.g., to enhance contact and promote ablative coupling with thetissue, as a cooling fluid, as an ablative fluid, or for any otherreason where an irrigated catheter can be and/or is used.

In addition, the irrigated collar 358 further serves a similar functionto that of the collar 50 shown in FIG. 4, to prevent the flexible sleeve338 from passing over the irrigated collar 358. By stopping the flexiblesleeve 338 behind the irrigated collar 358, the flexible sleeve 338 doesnot block or otherwise interfere with delivery of the fluid at the fluidports.

It is noted that the tip assembly 314 shown in FIG. 6 is provided onlyas one example of how the tip assembly might be implemented with anirrigated catheter. Of course other embodiments are also contemplated,for example, having multiple fluid ports along the length of the guideelement, different fluid ports at different locations and/or fordifferent types of fluids, and so forth. It is also noted that the tipassembly can be and/or is used with any types of fluid, including butnot limited to, cooling fluids and/or therapeutic fluids.

FIG. 7 shows another flexible sleeve 438 which can be and/or isimplemented with a tip assembly. FIG. 8 shows the tip assembly 414 ofthe catheter 10 shown in FIG. 1, wherein the tip assembly 414 includesthe flexible sleeve from FIG. 7 and a guide element 432. The tipassembly 414 can be and/or is coupled to the tube portion 12 of thecatheter 10 in FIG. 1 at one end, and provided through a sheath (notshown) for insertion into the patient's body.

The tip assembly 414 can include a flexible sleeve 438 having a proximalend 440 and a distal end 442. The flexible sleeve 438 is made of amaterial which enables the flexible sleeve 438 to conform to the shapeof the guide element 432 so that the flexible sleeve 438 can be slidover the guide element 432. In an exemplary embodiment, the flexiblesleeve 438 is made of a biologically compatible plastic or polymermaterial. Alternatively, the flexible sleeve 438 can be and/or is madeof any material and provided with a suitable coating (e.g., Teflon®coating).

The guide element 432 (FIG. 8) has a proximal end and a distal end. Thelength of the guide element 432 extending between the proximal end andthe distal end of the tip assembly 414 can be and/or is configurable ina desired shape. In this embodiment, the guide element 432 can be and/oris a mapping catheter 470 which is formed in a helical, circular shape,or in any other suitable shape. The mapping catheter 470 can include oneor more sensor electrodes 472. During use, the mapping catheter 470 canbe and/or is inserted adjacent the tissue so that the tissue can bemapped. Following the mapping operation, the flexible sleeve 438 can beand/or is advanced to the distal end of the mapping catheter 470 andoperated for the ablation procedure.

In this regard, the flexible sleeve 438 can include an insulated portion480 and an active portion 482. The active portion 482 can extend for alength of about 2 mm up to about 8-10 mm, although other lengths canalso be utilized depending on design/use considerations. The insulatedportion 480 is provided over a conducting portion 484. The conductingportion 484 is electrically connected to the active portion 482 on oneend, and to wiring or other electrical conductors provided through thelumen of the catheter 10 (FIG. 1) so that the conducting portion 484delivers electrical energy to the active portion 482 of the flexiblesleeve 438. Accordingly, in this embodiment the active portion 482 isthe ablation element 444. The ablation element 444 can be and/or isenergized for an ablation procedure, as is well known in the medicaldevices arts, for example, using RF energy. Accordingly, the ablationelement 444 is operable to form an ablative lesion when the ablationelement 444 (i.e., the active portion 482 on the flexible sleeve 438 isin contact with a target tissue.

It is noted that the active portion 482 can have any suitableconfiguration, including one or more active areas along the length ofthe flexible sleeve 438. In addition, any suitable number and/or type ofelectrodes and/or other sensors can also be provided, and will depend atleast to some extent on design considerations and the intended end-use.

As already discussed above, a controller can be and/or is operativelyassociated with the tip assembly 414. The controller can be and/or isoperated similarly to that already described above (e.g., including oneor more pull wires), and therefore is not shown and described again withreference to the tip assembly 441.

FIGS. 9a-b shows the flexible sleeve 438 in (a) a fully extendedposition relative to the guide element 431; and (b) in a fully retractedposition relative to the guide element 431. FIGS. 10a-e illustrates howthe flexible sleeve 438 can be and/or is moved over the guide element432 between the extended position and the retracted position. Asmentioned above, the tip assembly 414 can have any suitable shape and/orconfiguration. For purposes of illustration, in FIGS. 10a-e , the tipassembly 414 is shown having a more flattened configuration.

In FIG. 10a , the flexible sleeve 438 is shown as it can be and/or ismoved into the fully extended position. In the fully extended position(also shown in FIG. 9a ), the distal end 442 of the flexible sleeve 438is at the distal end 436 of the guide element 432. During and exemplaryprocedure, the flexible sleeve 438 is moved to the fully extendedposition prior to contacting the tissue and beginning the procedure.Once positioned against the tissue in the desired location, the ablativeelement 444 can be and/or is activated, e.g., by delivering RF energy tothe active region. Once a sufficient lesion has been formed in the fullyextended position, the user can gradually retract the flexible sleeve438, e.g., by operating the controller 438 to withdraw the flexiblesleeve 438 generally in the direction of arrows 448 a-c in FIG. 10a-c ,respectively, so that the flexible sleeve 438 is in a partiallyretracted position (FIGS. 10b and 10c ). The user can continue toretract the flexible sleeve 438 so that the flexible sleeve 438continues to retract until the flexible sleeve 438 is in a fullyretracted position, as illustrated in FIG. 10 d.

Again, the operation illustrated in FIG. 10a-d is not intended toillustrate discrete positions of the flexible sleeve 438, but rather toillustrate general movement from a fully extended position (as shown inFIG. 10a ) to a fully retracted position (as shown in FIG. 10d ). Thismotion can be and/or is a “fluid” or “smooth” motion (e.g., where theuser moves the flexible sleeve 438 at a constant velocity); or themotion can be and/or is more segmented (e.g., where the user maintainsthe flexible sleeve 438 at one or more of these positions for a periodof time before continuing moving the flexible sleeve 438). Specificoperation will depend on the desired end-result, among otherconsiderations for lesion formation.

FIG. 11 shows another tip assembly 514 having a generally linearconfiguration, with catheter 570 having electrodes 572 and activeportion 582. FIG. 12 shows another tip assembly 614 having a generallyflattened semi-circular configuration and flexible sleeve 638 withactive portion 682. FIGS. 13a-b show another tip assembly 714 having aguide wire 780 guide element 732 and a flexible sleeve 738. In FIGS. 13aand 13b , the flexible sleeve 738 is shown as it can be and/or isadvanced through the catheter sheath 712 (see also, sheath 12 in FIG. 1for reference). FIG. 13a shows the flexible sleeve 738 a fully extendedposition relative to the guide element 732. FIG. 13b shows the flexiblesleeve 738 in a fully retracted position relative to the guide element732. As already discussed above, the tip assemblies 514, 614, and 714shown in FIGS. 11, 12, and 13 a-b can be and/or is coupled through thesheath 712 (or tube portion 12 of the catheter 10 in FIG. 1) at one end,and provided through the sheath 712 for insertion into the patient'sbody.

The tip assemblies 514, 614, and 714 can include guide elements 532,632, 732, respectively, which can be and/or is configurable in a desiredshape. The tip assembly 614 can also include a flexible sleeve 538, 638,738. The flexible sleeve 538, 638, 738 is made of a material whichenables the flexible sleeve 538, 638, 738 to conform to the shape of theguide element 532, 632, 732 so that the flexible sleeve 538, 638, 738can be slid over the guide element 532, 632, 732.

The tip assembly tip assemblies 514, 614, and 714 are particularlysuited for ablation procedures wherein radio frequency waves aredelivered at the site of an abnormal pathway in the body. Radiofrequency(RF) energy can therefore be coupled to biological tissue surroundingthe catheter tip. Ablation procedures are typically used, for example,within the interior chambers of the heart to thermally ablate cardiactissue. Accordingly, the flexible sleeves 538, 638, 738 can comprise anablation element configured as the active portion, e.g., as alreadydescribed above with reference with FIGS. 7 and 8.

A controller can be and/or is operatively associated with the tipassemblies 514, 614, and 714. The controller can be and/or is operatedsimilarly to that already described above (e.g., including one or morepull wires), and therefore is not shown and described again withreference to the tip assemblies 514, 614, and 714.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

What is claimed is:
 1. A catheter comprising: a guide element includinga proximal end and a distal most end, the distal end configurable in acircular shape extending at least 180 degrees and defining a circularpath; a flexible sleeve conformable to the guide element so that theflexible sleeve slides over the guide element, the flexible sleeveincluding a proximal end and a distal end, the flexible sleeve includinga conducting element, the conducting element of the flexible sleeveincluding both an insulating portion and an active portion of theconducting element; a controller attached to the flexible sleeve, thecontroller operable to move the flexible sleeve at least part waybetween the distal end of the guide element and the proximal end of theguide element; at least one ablation element formed by the activeportion of the conducting element on the flexible sleeve at the distalend of the flexible sleeve, the at least one ablation element operableto form an ablative lesion when the flexible sleeve is adapted to be incontact with a contiguous volume of target tissue; and wherein theflexible sleeve is configured, during an ablation procedure, to beinitially positioned at the distal most end of the guide element, andretracted toward the proximal end of the guide element during theablation procedure, the retraction of the flexible sleeve along thecircular path creates a lesion on the target tissue substantiallyconforming to the circular shape of the guide element.
 2. The catheterof claim 1, wherein the guide element comprises one of a guide wire, amapping catheter, and a preformed member configured into the circularshape.
 3. The catheter of claim 1, wherein the conducting element ispartially covered by the insulating portion, and the conducting elementis electrically coupled to the active portion for delivering electricalenergy to the active portion.
 4. The catheter of claim 1, furthercomprising at least one electrode mounted to an outer surface of theflexible sleeve and at least one sensor mounted to an outer surface ofthe flexible portion.
 5. The catheter of claim 4, wherein the at leastone sensor comprises at least one of: a thermistor, a thermocouple, amapping sensor, and a contact sensor.
 6. The catheter of claim 1,wherein the circular shape of the guide element extends along atransaxial plane relative to a longitudinal axis of the catheter.
 7. Thecatheter of claim 1, wherein the guide element includes an irrigationconduit with at least one irrigation port.
 8. The catheter of claim 1,wherein the flexible sleeve forms both the insulating portion and theactive portion of the conducting element.
 9. The catheter of claim 1,wherein the insulating portion and the active portion are integralportions of the flexible sleeve.
 10. The catheter of claim 1, whereinthe flexible sleeve is coated over a portion of the conducting elementto form the insulating portion.
 11. A catheter comprising: a unitaryflexible tubing including a proximal end and a distal end definingsubstantially an entire length of the catheter; a guide elementincluding a proximal end and a distal most end, the distal end preformedin a circular shape extending at least 180 degrees and defining acircular path; a flexible sleeve conformable to the guide element sothat the flexible sleeve slides over the guide element, the flexiblesleeve including a proximal end and a distal end, the guide element andthe flexible sleeve insertable through the unitary flexible tubing, theflexible sleeve including a conducting portion, the conducting portionof the flexible sleeve including both an insulating portion and anactive portion; a controller attached to the flexible sleeve andextending through the unitary flexible tubing adapted for operationoutside of a body of a patient, the controller operable to affect travelof the flexible sleeve over the guide element in two directions; atleast one ablation element formed by an exposed portion of the activeportion at the distal end of the flexible sleeve, the at least oneablation element operable to form an ablative lesion when the flexiblesleeve is adapted to be in contact with a contiguous volume of targettissue; and wherein the travel of the flexible sleeve is constrainedbetween an extended position toward the distal most end of the guideelement and a retracted position toward the proximal end of the guideelement, and the travel of the flexible sleeve is configured to create alesion on the target tissue substantially conforming to the circularpath of the guide element in contact with the target tissue byretracting the flexible sleeve during an ablation procedure from theextended position to the retracted position of the guide element. 12.The catheter of claim 11, wherein the guide element comprises one of aguide wire or a mapping catheter, and wherein the circular shape of theguide element extends along a transaxial plane relative to the length ofthe catheter.
 13. The catheter of claim 11, wherein the active portionis in electrical contact with the conducting portion.
 14. A cathetercomprising: a flexible tubing defining substantially an entire length ofthe catheter; a guide including a proximal end and a distal most end,the distal end preformed in a circular shape that extends along atransaxial plane relative to the length of the catheter and defines acircular path; a flexible sleeve conformable to the guide so that theflexible sleeve slides over the guide, the flexible sleeve including aproximal end and a distal end, the guide and flexible sleeve insertablethrough the flexible tubing for positioning adjacent a tissue, theflexible sleeve including a conducting portion, the conducting portionof the flexible sleeve including both an insulated portion and an activeportion; a control attached to the flexible sleeve and extending throughthe flexible tubing for operation outside of a patient's body to movethe flexible sleeve back and forth over the guide means; and an ablationelement formed by an exposed portion of the active portion provided atthe distal end of the flexible sleeve, the ablation element operable toform an ablative lesion when the flexible sleeve is adapted to be incontact with a contiguous volume of target tissue; and wherein theflexible sleeve is configured to create a lesion on the contiguousvolume of the target tissue substantially conforming to the circularpath of the guide in contact with the target tissue by retracting theflexible sleeve during an ablation procedure from a distal most end to aproximal end of the guide.
 15. The catheter of claim 14, wherein theguide is at least one of a guide wire or a mapping catheter, and thecircular shape of the guide extends at least 180 degrees.
 16. Thecatheter of claim 14, wherein moving the flexible sleeve creates alesion on the tissue substantially conforming to the shape of the guidein contact with the tissue.
 17. The catheter of claim 14, wherein theinsulated portion surrounds part of the conducting portion; and theactive portion is in electrical contact with the conducting portion. 18.The catheter of claim 14, further comprising at least one electrodemounted to an outer surface of the flexible sleeve.